Experiments were conducted to characterize cerebrovascular endothelial cells (EC) lines derived from SJL-J mice with respect to their infectibility with Theiler's murine encephalomyelitis virus and vaccinia virus. In addition, the capacity of these cells to function as antigen- presenting cells in immune responses to these murine viruses was also studied. The EC cell line had interferon-gamma inducible expression of MHC antigen. Infection with Theiler's murine encephalomyelitis virus also influenced the expression of MHC molecules by these cells. The data indicated that these EC cultures could not stimulate T lymphocyte proliferation or function as targets for cytolysis by Theiler's murine encephalomyelitis cytolytic immune spleen cells. However, EC lines were able to present viral antigen to vaccinia virus immune spleen cells and act as targets for cytotoxic T cells from vaccinia virus immune mice. The data indicate cerebrovascular EC cultures are a valuable resource for the study of biology and immune response to murine viruses, such as Theiler's virus. These findings have important implications regarding pathogenic mechanisms of adoptively transferred experimental allergic encephalomyelitis (EAE) which has been shown to involve cerebrovascular EC.